Protection of audio or video data in a playback device

• US 20080165961A1
• Filed: 01/08/2007
• Published: 07/10/2008
• Est. Priority Date: 01/08/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Farrugia, Augustin J., Lerouge, Julien, Fasoli, Gianpaolo
• Granted Patent: US 8,256,005 B2
• Time in Patent Office: Days
• US Class Current: 380/202
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/41407 embedded in a portable device, e.g. video client on a mobile phone, PDA, laptop constructional details of equipment or arrangements specially adapted for portable computer application G06F1/1626; arrangements specially adapted for mobile receivers in broadcast systems H04H20/57
• CPC Class Codes: H04N 21/4325 by playing back content from the storage medium reproduction of recorded television signals H04N5/76; reproduction of recorded television signals H04N9/79
• CPC Class Codes: H04N 21/4398 involving reformatting operations of audio signals details of audio signal transcoding G10L19/173
• CPC Class Codes: H04N 21/4402 involving reformatting operations of video signals for household redistribution, storage or real-time display details of conversion of video standards at pixel level H04N7/01; video transcoding H04N19/40; adapting incoming signals to the display format of the display terminal G09G5/005; media handling at the source in data packet switching networks H04L65/764
• CPC Class Codes: H04N 21/4408 involving video stream encryption, e.g. re-encrypting a decrypted video stream for redistribution in a home network
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/163 by receiver means only
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

Method and apparatus to prevent hacking of encrypted audio or video content during playback. Hackers, using a debugging attachment or other tools, can illicitly access encrypted data in memory in a playback device when the data is decrypted during playback and momentarily stored in digital form. This hacking is defeated here by methodically “poisoning” the encrypted data so that it is no longer playable by a standard decoder. The poisoning involves deliberate alteration of certain bit values. On playback, the player invokes a special secure routine that provides correction of the poisoned bit values, for successful playback.

Claims

1. A method of playing secure video or audio data on a playback device, comprising the acts of:

receiving encrypted audio or video data from storage in the device;

decrypting the data;

parsing the decrypted data into portions;

in each portion, detecting the values of at least one predetermined bit location or other indicator;

if the detected value or indicator does not match a predetermined value, decoding the portion, and playing the coded portion;

if the detected value matches the predetermined value or indicator, accessing a routine from a secure memory location in the playback device; and

decoding the portion using the routine and playing the decoded portion.

2. The method of claim 1, wherein the decoding is according to the AAC or H.264 standards.

3. The method of claim 1, wherein each portion is a data frame or data packet.

4. The method of claim 1, wherein the predetermined bit location is in at least one of a section data block, a scale factor block, and a spectral data block.

5. The method of claim 1, wherein the values of a plurality of predetermined bit locations are detected.

6. The method of claim 2, wherein the matching value of the predetermined bit location is a reserved value according to the standard.

7. The method of claim 1, wherein the routine decodes the portion.

8. The method of claim 1, wherein the routine accesses data from a secure memory location to substitute for the value in the predetermined bit location.

9. A computer readable medium carrying computer code for carrying out the method of claim 1.

10. Computer enabled apparatus for carrying out the method of claim 1.

11. The method of claim 1, wherein the playback device is a computer or audio or video player.

12. The method of claim 1, wherein the values of at least one predetermined bit location are not detected.

18. The apparatus of claim 2, wherein the matching value of the predetermined bit location is a reserved value according to the standard.

13. Apparatus for playing secure video or audio data, comprising:

storage for storing audio or video data in encrypted form;

a decryptor coupled to the storage to decrypt the data;

a parser coupled to the decryptor to parse the decrypted data into portions;

a logic element coupled to the parser to detect the value of at least one predetermined bit location or other indicator in each portion, and to determine if the value of the at least one predetermined bit location or indicator matches a predetermined value, and accessing a routine from a secure memory location in the apparatus in event of a match;

wherein the portion is decoded for play using the routine, and

wherein the portion is otherwise not decoded for play in the absence of a match.

14. The apparatus of claim 13, wherein the decoding is according to the AAC or H.264 standards.

15. The apparatus of claim 13, wherein each portion is a data frame or data packet.

16. The apparatus of claim 13, wherein the predetermined bit location is in at least one of a section data block, a scale factor block, and a spectral data block.

17. The apparatus of claim 13, wherein the values of a plurality of predetermined bit locations are detected.

19. The apparatus of claim 13, wherein the routine decodes the portion.

20. The apparatus of claim 13, wherein the routine accesses data from a secure memory location to substitute for the value in the predetermined bit location.

21. A computer readable medium carrying computer code for carrying out the apparatus of claim 13.

22. The apparatus of claim 13, wherein the apparatus is a computer or audio or video player.

23. A method of providing secure audio or video data for a playback device, comprising the acts of:

receiving encrypted audio or video data from a source external to the playback device;

decrypting the data;

parsing the decrypted data into portions;

in each portion, identifying according to a predetermined criteria if a value of a predetermined bit location is to be modified;

if the value is to be modified, modifying the value of the predetermined bit location;

reassembling the portion with the modified value;

encoding the portion;

re-encrypting encoded portion; and

storing the re-encrypted portion in memory in the device for later playback.

24. The method of claim 23, wherein the decoding is according to the AAC or H.264 standards.

25. The method of claim 23, wherein each portion is a data frame or data packet.

26. The method of claim 23, wherein the predetermined bit location is in at least one of a section data block, a scale factor block, and a spectral data block.

27. The method of claim 23, wherein the values of a plurality of predetermined bit locations are detected.

28. The method of claim 24, wherein the matching value of the predetermined bit location is a reserved value according to the standard.

29. The method of claim 23, wherein the routine decodes the portion.

30. The method of claim 23, wherein the routine accesses data from a secure memory location to substitute for the value in the predetermined bit location.

31. A computer readable medium carrying computer code for carrying out the method of claim 23.

32. Computer enabled apparatus for carrying out the method of claim 23.

33. The method of claim 23, wherein the playback device is a computer or audio or video player.

34. Apparatus for playing secure video or audio data, comprising:

a port adapted to receive encrypted audio or video data from a source external to the playback apparatus;

a decryptor coupled to the port for decrypting the received data;

a parser coupled to the decryptor for parsing the decrypted data into portions;

a logic element coupled to the parser and which identifies, according to a predetermined criterion, if a value of a predetermined bit location in each portion is to be modified;

a secure memory location coupled to the logic element;

wherein the logic element modifies the value of the predetermined bit location according to a routine stored in the secure memory location, and reassembles the portion;

an encoder coupled to the logic element and which encodes the portion;

an encryptor coupled to the encoder and which re-encrypts the encoded portion; and

storage coupled to the encryptor and which stores the re-encrypted portion for later playback.

35. Apparatus for video or audio play, comprising:

an input portion including;

a port adapted to receive encrypted audio or video data from a source external to the playback apparatus;

a decryptor coupled to the port for decrypting the received data;

a parser coupled to the decryptor for parsing the decrypted data into portions;

a logic element coupled to the parser and which identifies, according to a predetermined criterion, if a value of a predetermined bit location in each portion is to be modified;

a secure memory location coupled to the logic element, wherein the original value of the predetermined bit location is stored in the secure memory location; and

wherein the logic element modifies the value of the predetermined bit location, and reassembles the portion;

an encoder coupled to the logic element and which encodes the portion;

an encryptor coupled to the encoder and which re-encrypts the encoded portion; and

storage coupled to the encryptor and which stores the re-encrypted portion for later playback;

and an output portion comprising;

a logic element coupled to the parser to detect the value of at least one predetermined bit location in each portion, and to determine if the value of the at least one predetermined bit location matches a predetermined value, and accessing a routine from a secure memory location in the apparatus in event of a match;

wherein the portion is decoded for play using the routine, and

wherein the portion is otherwise not decoded for play in the absence of a match.